The maturity of electronic commerce and acceptance of the Internet as a daily tool by a continually growing user base of millions of users intensify the need for communication engineers to develop techniques for enhancing network performance. With the advances in processing power of desktop computers, the average user has grown accustomed to sophisticated multimedia applications, which place tremendous strain on network resources. Given the variety of users and applications, the need for guarantees from the network service provider in terms of Quality of Service (QoS) is evident. However, current approaches to providing QoS levels are in its infancy as no prevailing QoS mechanisms have been adopted.
Modern satellite communication systems provide a pervasive and reliable infrastructure to distribute voice, data, and video signals for global exchange and broadcast of information. These satellite communication systems have emerged as a viable option to terrestrial communication systems, particularly in the arena of Internet access. As the popularity of the Internet continues to grow in unparalleled fashion, the communication industry has focused on improving user response time. Although satellite based Internet service addresses the problem of providing universal Internet access in that satellite coverage areas are not hindered by traditional terrestrial infrastructure obstacles, the deployment of satellite based access services is tempered by the challenges of minimizing delay and increasing throughput in a bandwidth constrained system. Ensuring QoS guarantees over this bandwidth constrained system introduces additional challenges.
The Internet operates according to internetworking protocols that rely on a best-effort delivery model. This model is suitable for traffic that is non-real-time, such as file transfers, and emails. With the development of sophisticated real-time applications, such as streaming audio and video, the best-effort delivery model is unsatisfactory, as delay, particularly variable delay, negatively impacts the applications.
Additionally, the Internet is primarily a router-based network. The routers support classification of traffic based on statically known information. With multimedia streams, however, the routers cannot readily identify the associated dataflow because these multimedia applications dynamically negotiate their connections.
One conventional approach involves the deployment of the Resource Reservation Protocol (RSVP), which is used by applications to request specific quality of service (QoS) from the network. To make a resource reservation at a node, a RSVP daemon communicates with an admission control module and a policy control module to determine whether the user is permitted to make the reservation and whether sufficient network resources are available to support the requested QoS. One drawback with RSVP is that the RSVP services are executed at the end hosts, and require RSVP support by the intermediate nodes; moreover, the RSVP services are not widely used in the end hosts as to require action by the intermediate nodes. Another drawback is that RSVP only provides a mechanism to request resources, without guaranteeing that the network resources will be available.
Based on the foregoing, there is a clear need for improved approaches for providing QoS services in a bandwidth constrained system. There is also a need for a mechanism that provides guarantees on the availability of network resources. There is a further need to deploy a QoS mechanism that requires minimal modification of network nodes and minimizes deployment costs.